I use Medium because I think their blogging software is superior to their competitors (WordPress). If there was something out there as good as Medium that I could install on my own servers I might do that. This seems to be the hierarchy of blogging software to me: Medium > WordPress > Blogger

I'm sure there are some other really great options out there that I've never heard of. And I'm sure if you spend a great deal of time looking you can find kickass WordPress themes. But the default WordPress themes are pretty weak, and Blogger is really weak.

So anyway, that's I use Medium to host my blog, because their blogging software simply kicks ass.